1. Field of the Invention
This invention relates to a device for determining whether containers of ethylene oxide have developed leaks. More particularly, this invention relates to a device for detecting the presence of ethylene oxide gas.
2. Description of the Prior Art
Containers of volatile materials must often be packed in crates for shipping. One specific example is the packing for shipping of fuel air explosive warheads which commonly contain the volatile material, ethylene oxide.
While such containers are crated, it is desirable to be able to monitor them and determine whether or not they have developed leaks. This is done by monitoring for ethylene oxide gas.
In the past, various techniques have been used to monitor for ethylene oxide gas. Among these have been the use of infrared spectroscopy, microwave spectroscopy, hydrogen flame ionization, semiconductor gas-electric transduction, refracted index, electron capture, catalytic oxidation, Van der Waal's adsorption and chemical reaction with color change. Except for the last method, an energy source is required. Accordingly, the last method, which does not require an energy source, is preferred. However, the device presently utilized in carrying out the chemical reaction with color change technique has a serious drawback. That drawback is the fact that it is too sensitive.
The presently used device is so sensitive that it will detect ethylene oxide vapor present due to mere spillage on the surface of a container while the container was being filled. In addition, it is affected by heat, light, moisture and organic compounds other than ethylene oxide.
The presently used device employs, as the indicator, a small paper disc coated with approximately 0.018 grams of magnesium bromide hexahydrate and 0.003 grams of a combination of 1,8-dihydroxyanthroquinone (chrysazin) and polyvinyl acetate binder. The ethylene oxide reacts with the magnesium bromide hexahydrate to produce bromohydrin and magnesium hydroxide. The magnesium hydroxide, in turn, reacts with the chrysazin to cause a change in color from yellow to red.
Ethylene oxide will react with a number of other salts and water to produce similar products. This fact is sometimes used to make modifications of the aforementioned device for detecting ethylene oxide. Other materials that have been investigated include potassium thiocyanate, magnesium chloride and sodium thiosulfate. Devices utilizing these materials all have the sensitivity drawback of the presently used device.